You maybe don't allow pages to choose their own font? From what I understand it works by making a font that maps Latin characters to random Unicode points. So, unless for a specific text its respective font is used, text will appear gibberish.
edit: Saw you said you use an old phone. Found those fonts are in woff format. Older Android phones don't have support for it.
edit: Saw you said you use an old phone. Found those fonts are in woff format. Older Android phones don't have support for it.